Who wins this fight?

I do not doubt at all, that John was more talented boxer, than Danny. If Sull trained and boxed presently he easily would knock out him.

Fight will end in a draw :)

john sullivan everytime, even rita sullivan would stop williams

I don´t know too much about Sullivan. But he did use to fight bare-knuckled and was used to fight for 20-30 rounds, so I´m guessing he was a tough sob. He was only knocked out once, in his last fight, probably over the hill. Further, he was not a small heavyweight, weighing somewhere around 200lbs.

Considering how much the sport of boxing has evolved, I can imagine Williams defeating Sullivan by decision in a 10 or 12 rounder. Though I am not sure! Williams is by no means a great fighter, so I would not be surprised with a Sullivan victory. If they fought during Sullivans era, Sullivan kicks Williams´ behind and knocks him out at some point. No way Williams would have the stamina to go keep up with Sullivan.